Methods

Pts must have HER2-positive MBC or locally advanced BC and no prior non-hormonal anti-cancer therapy in the metastatic setting. The initial dose of P is 840 mg followed by 420 mg every 3 weeks (Q3W); the initial dose of T is 8 mg/kg followed by 6 mg/kg Q3W; V is administered at 25 mg/m2 in Cycle 1 followed by 30–35 mg/m2 on Days 1 and 8 of each subsequent cycle Q3W. The primary endpoint is objective response rate based on best overall response. Secondary endpoints include PFS, OS and safety.

Results

C1 and C2 are fully enrolled with 106 and 107 treated pts, respectively. At initial diagnosis, 32% (C1) and 25% (C2) of pts had MBC. In the neoadjuvant and adjuvant settings, 56% (C1) and 32% (C2) of pts had received chemotherapy, including a taxane (39% and 21%) or an anthracycline (39% and 26%); 41% and 18% had prior T exposure. At the data cut-off of 5 March 2014, the median number of cycles received in C1 was 15 for P + T and 9.5 for V, and in C2 was 10 for P + T and 9 for V. AEs were reported by 99% (C1) and 98% (C2) of pts. Grade ≥3 AEs were reported by 59% (C1) and 69% (C2) of pts. The grade ≥3 AEs in ≥5 pts in either cohort were neutropenia, leucopenia, diarrhoea, fatigue, febrile neutropenia, hypertension and asthenia. Serious AEs were reported by 29% (C1) and 33% (C2) of pts. Interim best overall response data from C1 will be presented.

Conclusions

These interim safety data show that P + T + V has an acceptable AE profile with no unexpected safety signals. Administration of P + T sequentially, or in a single saline infusion bag, is feasible from a safety standpoint. Interim best overall response data from C1 will be presented.

Disclosure

M. Andersson: has participated in an advisory board on behalf of Roche; T. Petit: has participated in an advisory board on behalf of Roche; U. Freudensprung: is an employee of Roche; S. Robb: is an employee of Roche; E. Restuccia: is an employee of and owns stocks in Roche. All other authors have declared no conflicts of interest.